1. Field of Invention
The present invention relates generally to apparatuses and methods for dynamic control of surface morphology, and more specifically, but not by way of limitation, to two-dimensional fluid-driven bubble actuator arrays.
2. Description of Related Art
Examples of fluid-driven actuator arrays are disclosed in U.S. Pat. No. 6,092,249; and U.S. Pat. No. 5,267,365.
Devices that require contact with a user's body such as prosthetic limbs, beds, seat cushions, or helmets pose the risk for discomfort and sores, particularly when the user has limited mobility. In almost all of these devices, consistent conformal contact between the device and the human body is desirable for both comfort and safety.
With regards to prosthetic limbs, the volume of a residual limb changes through the gait cycle and throughout the day (Board, W. 2001; Sanders, Harrison et al. 2009). This may be particularly evident in transtibial amputations, as the tissue consistency from anterior to posterior is often markedly different; however, this variation in tissue types exists in transfemoral amputations as well (Convery and Buis 1998). Residual limb volume changes can result in excessive pressures, as well as shear and frictional forces upon a residual limb in a prosthesis socket. If conditions between a residual limb and prosthesis socket are suboptimal, discomfort, skin irritation, and/or pressure ulcers may result. Studies have reported that among non-vascular transfemoral amputees one of the most frequent complaints is sore skin and/or irritation from prosthetic limb sockets. (Hagberg and Branemark 2001).
Current devices and methods designed to ensure fit and comfort for prostheses are generally passive. For example, some amputees place layers of socks over their residual limb before insertion into a prosthesis socket in an attempt to achieve a better fit or to compensate for residual limb volume changes. Additionally, certain systems may use vacuum-assisted prosthesis sockets, and others use air-cushioned sockets. Existing systems, however, are generally incapable of modulating or distributing the pressure exerted on the residual limb or actively compensating for residual limb volume changes.
Prosthetic limb users are not the only individuals susceptible to contact related skin damage. Pressure ulcers may be caused by prolonged contact between a bed or chair and a part of the body. Due to their immobility, stroke patients and individuals with spinal cord injuries may be particularly susceptible to such pressure ulcers.
Currently, safeguards against ulcers include frequent skin examination, body weight shifting, and monitoring of moisture accumulation. Additionally, certain cushions or water beds are available, but these devices still require outside human intervention to frequently move the individual to avoid pressure ulcer formation. Existing methods may be insufficient to prevent pressure ulcers because these methods are not capable of actively modulating or distributing the pressure exerted on the individual. Such existing methods may also require extensive human resources.
Existing methods for impact protection may involve foam cushioning disposed on and/or within a wearable device (e.g., protective gear, such as, for example, helmets, pads, body armor, and/or the like). However, such existing methods may not ensure consistent conformal contact between the wearable device and a user of the wearable device (e.g., existing crash helmets may be unable to ensure consistent conformal contact between an inner surface of the helmet and a user's head and/or may over pressurize some parts of the user's head). Furthermore, current methods may be unable to effectively distribute forces from an impact (e.g., whether spatially and/or temporally) to minimize damage to the user.
Helmets may also be used for cranial remodeling of an infant skull. Plagiocephaly, an asymmetrical distortion of the skull, is a common condition in infants caused by both genetic malformities and external factors. One of the most effective treatments for correcting this asymmetrical distortion is the use of an orthotic helmet. Orthotic helmets apply pressure to the non-deformed section of the head so that the skull grows in the appropriate direction, thereby rounding the head. Currently, the pressure exerted by an orthotic helmet generally cannot be precisely determined. Frequent doctor visits (every one to four weeks for a period of 3 to 6 months) and helmet reconfigurations are required for proper treatment. Existing methods of cranial remodeling are not capable of actively reshaping the skull as it grows or exerting known pressures on the skull as prescribed by a doctor.
Robotic manipulators are typically used to grasp and move objects in a number of degrees of freedom, and are used in a wide variety of applications, including, but not limited to, manufacturing, surgery, human/robot interactions, produce picking, and/or the like, and may be particularly suited to applications in which human presence is dangerous and/or otherwise undesirable (e.g., space operations, working with toxic substances, and/or the like). The successful grasping and/or moving of objects can largely depend on the degree of conformal contact between the object and the manipulator. For example, insufficient conformal contact between the manipulator and the object can result in the object becoming separated from the manipulator during grasping and/or moving, and too strong of a conformal contact can cause damage to the object. Ensuring such adequate conformal contact typically requires precise manipulator movements and/or manipulators specifically designed for interaction with the particular object being manipulated. Depending on the object, this can require the manipulator to be able to move in multiple and complex degrees of freedom. Current robotic manipulators may be capable of conforming to an object that is well-defined (e.g., the material properties and/or shape of the object are known to the robotic manipulator and/or to the robotic manipulator controller). However, for undefined objects or objects that the manipulator has not been designed and/or configured to grasp, the grasping can be suboptimal, which may result in separation of the object from the manipulator and/or damage to the object.
Prosthetic manipulators can function similarly to robotic manipulators, and are typically either myoelectric or switch based. In either type, body movements such as muscle contractions can be used to actuate the prosthetic manipulator. As with robotic manipulators, successful grasping and/or movement of an object may require adequate conformal contact between the manipulator and the object. Current prosthetic manipulators may not be capable of adequately grasping the wide variety of objects a user may wish to interact with, and may require the user to change or adjust the prosthesis. Additionally, fragile, slippery, or objects that are otherwise difficult to grasp may require a degree of precision of manipulator control that current prosthetic manipulators are unable to provide.